The present invention is directed to a novel vaccine, and to a method of protecting poultry against Newcastle disease. More particularly, the invention relates to a safe and effective marker vaccine against Newcastle disease, and to reagent kits and assay methods for testing poultry that will furthermore permit poultry keepers to distinguish vaccinated members of the flock from those that may have been infected with the wild-type Newcastle disease virus. The invention also relates to novel mutant immunogens useful in a vaccine against Newcastle disease.
Newcastle disease (ND) is a serious illness of poultry which is often times fatal, and therefore can result in significant economic losses. The ailment is caused by the Newcastle disease virus (NDV), a virus belonging to the genus Paramyxovirus of the family Paramyxovirdae. Within the avian paramyxoviruses, 9 distinct serotypes designated PMV-1 to PMV-9 are recognized; NDV is PMV-1 or serotype 1. A strain of NDV has now been designated xe2x80x9cWiltenbergxe2x80x9d (also xe2x80x9cWiltenburgxe2x80x9d), or NDW strain, as per U.S. Pat. No. 5,149,530, incorporated herein by reference.
From the viral envelope of NDV two types of surface projections (spikes) protrude. One is composed of a glycosylated protein which encompasses both hemagglutinating (H) and the neuraminidase (N) activity of the virion (HN glycoprotein). The other consists of glycoprotein F which is responsible for cell fusion, hemolysis and virus penetration. The carbohydrate-free matrix protein M which is incorporated into the inner side of the membrane, serves as a binding site for the nucleocapsid and is probably involved in the aggregation of the HN and F glycoproteins during virus budding from the plasma membrane.
Antibodies that greatly mediate immunity are produced against all three proteins. Those directed against the HN or F protein alone are protective.
Newcastle disease affects many commercial domestic poultry members, including chickens, turkeys, pheasants, guinea fowl, ducks, geese and pigeons. In addition, it can also afflict a wide range of captive and free-ranging semi-domestic and free-living birds including migratory waterfowl. Caged or aviary birds can also be affected.
The Newcastle disease virus enters the animal""s body via the respiratory and intestinal tract. Air-borne particles of less than 5 microns disperse in the entire respiratory tract, including the air sacs. Particles of greater than 5 microns are caught in the conjunctivae, nose and trachea down to the bifurcation. In the trachea, the virus is spread by the cillary action and by cell-to-cell infection. After initial multiplication at the introduction site, virulent virus is then carried to the spleen, liver, kidney and lungs. The virus eventually invades the brain, whereupon many birds start dying.
Symptoms of Newcastle disease are primarily respiratory and nervous. Gasping is common. Nervous symptoms include unilateral and bilateral paralysis of wings and/or legs, circular movements, bobbing/waving movements of the head and neck, and spasms of the wing, neck or leg muscles. General symptoms can include loss of appetite and decreased egg laying, often by as much as 40% or more.
Mortality can vary, depending on the properties of the virus involved and the immune status of the particular flock. Generally, those strains that kill quickly spread less between affected birds than those killing more slowly. In addition, a long asymptomatic carrier state has been presumed to occur in certain species of poultry such as chickens. The greatest risk of spreading the disease during an outbreak comes form movement of people and equipment. Due to centralization of many processes in the poultry industry, there is considerable traffic of personnel and equipment moving from one flock to another.
Many vaccines have now been developed to protect birds from the onset of Newcastle disease. Live antigen vaccines and attenuated antigen vaccines may be administered by eye or nose drop, or via spraying or drinking water. Inactivated vaccines can also provide protection, often at times without post-vaccinal respiratory reactions. Many of these are oil emulsion vaccines in which an oily adjuvant is utilized to enhance the immunogenic properties of the vaccine antigen. Vaccines may also be administered in ovo to developing chick embryos. In this way, better precision may sometimes be obtained.
U.S. Pat. Nos. 5,149,530; 5,250,298; 6,348,197; 5,750,111 and 5,733,556 each address the current state of the art as it relates to vaccines against the Newcastle disease virus. Some of the cited references further address combination vaccines, e.g. those containing one or more antigens directed to additional poultry ailments besides Newcastle disease.
Unfortunately, at present there appears to be no way to distinguish vaccinated members of a flock from those unvaccinated members that have been afflicted with the virulent, xe2x80x9cwild-typexe2x80x9d version of Newcastle disease virus. In both instances, antibodies are produced in the animals"" bodies. However, current vaccination immunogens against NDV induce antibodies that are very often indistinguishable from antibodies found after infection with virulent, infectious NDV.
What is therefore needed in the art is a new vaccine against the Newcastle disease virus. This vaccine should be safe and effective in preventing Newcastle disease when administered by eye or nose drop, or via spraying or drinking water, or in ovo to poultry. It should also permit poultry personnel to distinguish vaccinated members from unvaccinated members of the flock that have been afflicted with Newcastle disease. Development of a new vaccine should also permit the development of a reagent kit to assess whether an animal has been properly vaccinated, or has been infected with virulent Newcastle disease, or perhaps has been vaccinated with a more conventional NDV vaccine.
As part of the invention, there is provided a vaccine against Newcastle Disease virus, comprising about 100-109 EID50 of a mutant immunogen from the NDW strain of the Newcastle Disease virus, wherein the mutant immunogen lacks the antigenic binding site on the F glycoprotein recognized by the monoclonal antibody designated mAb 54.
Also provided is a mutant immunogen of Newcastle Disease virus identified as the strain deposited with the CNCM under accession number # I-2928. This mutant immunogen is suitable as a master seed virus in further developing an ND vaccine. The invention also provides for an immunogen of ND virus having the immunogenic characteristics of the deposited strain above.
There is also provided a method of protecting a poultry animal from Newcastle Disease, which comprises administering to the animal a vaccine containing about 100-109 EID50 of a mutant immunogen from the NDW strain of the Newcastle Disease virus, wherein the mutant immunogen lacks the antigenic binding site on the F glycoprotein recognized by the monoclonal antibody mAb 54.
The invention is also directed to a reagent kit for detecting inoculation via mutant immunogen against Newcastle Disease, comprising a standard NDV antigen and an illuminating antibody, wherein said illuminating antibody binds to said antigen in sera from inoculated birds, but does not bind to said antigen in sera from uninoculated birds.
There is further provided a method of generating a Newcastle Disease virus mutant immunogen useful in a vaccine against Newcastle Disease, which comprises growing Newcastle Disease virus in the presence of the monoclonal antibody designated mAb 54, such that said mutant immunogen develops and grows in the presence of said monoclonal antibody and is not neutralized by said monoclonal antibody. The mutant immunogen lacks the binding site on the F glycoprotein for an mAb54, and therefore is not neutralized by this antibody.
Also set forth is a mutant immunogen which is derived from the nucleotide sequence shown in Seq. ID No. 1. This partial nucleotide sequence codes for the F glycoprotein of the immunogen which lacks the binding site for the monoclonal antibody in mAb54. The amino acid sequence shown in Seq. ID No. 2 thereby represents the corresponding partial sequence of the F glycoprotein of Newcastle Disease virus.
The invention thereby also provides an immunogen of Newcastle Disease virus having the immunogenic characteristics of the mutant immunogen with the amino acid sequence shown in Seq. ID No. 2.
The invention further provides a mutant immunogen of Newcastle Disease virus in which the amino acid serine, normally found at position 157 in the wild-type NDW strains of virus, is replaced with arginine.
The invention additionally provides a reagent kit and method to assess whether a poultry animal has been vaccinated according to the invention as hereinafter described, or has been otherwise vaccinated using another NDV vaccine or has been infected with a wild-type ND virus.
Further objects and features of the invention will become apparent from the detailed description and the claims set forth herein below.